It is required for some facilities such as atomic power plants and thermal power plants that cables in the facilities have heat resistance or fire resistance against extraordinary accidents, e.g., fire. The heat resistance or fire resistance of cables is usually realized by covering the cables with a heat-absorbing material.
Conventional heat-absorbing materials include a water-containing polymer absorber and aluminum hydroxide hydrate. When heated, the polymer absorber absorbs heat, and the aluminum hydroxide hydrate absorbs heat by using water molecules (crystal water) contained therein.
However, the conventional heat-absorbing materials are bulky and heavy. Thus it is difficult to replace the covering of cables after laying cables since a working area for the exchange is narrow.
The polymer absorber is usually packed. If the package is broken, water evaporates at room temperature so that the polymer absorber becomes unable to function.
The absorber using aluminum hydroxide hydrate has a defect that cables are damaged before the hydrate decomposes since the decomposition temperature of hydrate is higher than the heatproof temperature of cables.
From the above, a heat-absorbing material is needed which does not require exchange, can be arranged in a small place, is lightweight and can efficiently absorb heat.
Magnesium phosphate hydrates are known as a heat-absorbing material (Patent Documents 1 and 2).